Electroluminescent device

ABSTRACT

Disclosed are electroluminescent devices that comprise organic layers that contain dibenzofuran compounds. The compounds are suitable components of, for example, blue-emitting, durable, organo-electroluminescent layers. The electroluminescent devices may be employed for full color display panels in, for example, mobile phones, televisions and personal computer screens.

This is a divisional of copending U.S. application Ser. No. 13/164,016, filed on Jun. 20, 2011, which is a divisional of copending U.S. application Ser. No. 11/921,050, filed Nov. 26, 2007, which is a national stage application of international application No. PCT/EP06/062483, filed May 22, 2006.

The present invention relates to electroluminescent devices that comprise organic layers that contain dibenzofuran compounds. The compounds are suitable components of, for example, blue-emitting, durable, organo-electroluminescent layers. The electroluminescent devices may be employed for full color display panels in, for example, mobile phones, televisions and personal computer screens.

H. O. Wirth et al., Die Makromolekulare Chemie 86 (1965) 139-167 describes the synthesis and properties of oxydo-p-oligophenylenes. The following two dibenzofuran compounds are described therein:

JP9151182 discloses dibenzofurandiamine derivatives, which are suitable as a positive hole transporting agent, etc., in electrophotographic photoreceptor, solar cell, electroluminescence element etc. The dibenzofurandiamine derivatives are represented by the following formula

wherein R₁ to R₅ are each a halogen, a (substituted)alkyl, a (substituted)alkoxy, a (substituted)aryl or (substituted) aralkyl; (a), (b), (c) and (d) are each 0-5; (e) is 0-6. The following compounds are explicitly disclosed in JP9151182:

JP2004311404 discloses compounds having at least one biaryl part structure for use in OLED application. The dimeric dibenzofuran compound shown below is explicitly mentioned.

WO03105538 relates to benzotriazole compounds and their use in OLED application. The dimeric benzotriazole compound shown below is explicitly mentioned.

The compounds shown below are also known:

(J. Chem. Soc. (1962) 5291,

(J. Chem. Soc. (1962) 5291,

(J. Org. Chem. 46 (1981) 851-855),

(Bull. Chem. Soc. Japan 9 (1934) 55), and

(Bull. Chem. Soc. Japan 9 (1934) 55).

Surprisingly, it was found that luminescent devices, which are high durability besides high in the efficiency of electrical energy utilisation and high in luminance, can be obtained if specific benzofuran compounds are used, especially as light emitting substances.

Accordingly, the present invention relates to compounds of the formula

wherein R⁸¹, R⁸², R⁸³, R⁸⁴, R⁸⁵, R⁸⁶, R⁸⁷, R⁸⁸, R⁹¹, R⁹², R⁹³, R⁹⁴, R⁹⁵, R⁹⁶, R⁹⁷, R^(91′), R^(92′), R^(93′), R^(94′), R^(95′), R^(96′) and R^(97′) are independently of each other H, —OR²⁰¹, —SR²⁰² and/or —NR²⁰³R²⁰⁴, C₁-C₂₄alkyl; C₁-C₂₄alkyl, which is substituted by E and/or interrupted by D; C₂-C₁₈alkenyl, C₂-C₁₈alkenyl, which is substituted by E, C₃-C₈cycloalkyl, C₃-C₈cycloalkyl, which is substituted by G, aryl, aryl, which is substituted by G, heteroaryl, or heteroaryl, which is substituted by G, silyl,

SiR⁶²R⁶³R⁶⁴, —CN, cyclic ether, —B(OR⁶⁵)₂ and/or halogen, especially fluorine, or R⁸¹ and R⁸², R⁸² and R⁸³, R⁸³ and R⁸⁴, R⁸⁵ and R⁸⁶, R⁸⁶ and R⁸⁷, R⁸⁷ and R⁸⁸, R⁹⁷ and R⁹⁶, R⁹⁶ and R⁹⁵, R⁹⁵ and R⁹⁴, R^(97′) and R^(96′), R^(96′) and R^(95′), R^(95′) and/or R^(94′), and/or two of the groups R⁹¹, R⁹² and R⁹³ or R^(91′), R^(92′) and R^(93′), which are in neighbourhood to each other, together form a group

wherein A⁴¹, A⁴², A⁴³, A⁴⁴, A⁴⁵, A⁴⁶ and A⁴⁷ are independently of each other H, halogen, hydroxy, C₁-C₂₄alkyl, C₁-C₂₄alkyl which is substituted by E and/or interrupted by D, C₁-C₂₄ perfluoroalkyl, C₅-C₁₂cycloalkyl, C₅-C₁₂cycloalkyl which is substituted by G and/or interrupted by S—, —O—, or —NR⁵—, C₅-C₁₂cycloalkoxy, C₅-C₁₂cycloalkoxy which is substituted by E, C₆-C₂₄aryl, C₆-C₂₄aryl which is substituted by G, C₂-C₂₀heteroaryl, C₂-C₂₀heteroaryl which is substituted by G, C₂-C₂₄alkenyl, C₂-C₂₄alkynyl, C₁-C₂₄alkoxy, C₁-C₂₄alkoxy which is substituted by E and/or interrupted by D, C₇-C₂₅aralkyl, C₇-C₂₅aralkyl, which is substituted by G, C₇-C₂₅aralkoxy, C₇-C₂₅aralkoxy which is substituted by E, or —CO—R⁸, M is a bonding group, such as a single (direct) bond, —CO—, —COO—; —S—; —SO—; —SO₂—; —O—; C₁₂alkylene, C₂-C₁₂alkenylene, or C₂-C₁₂alkinylene, which are optionally interrupted by one or more —O—, or —S—; or a group [M¹]_(n), wherein n is an integer 1 to 20, M¹ is arylene, or heteroarylene, which is optionally substituted by G, especially naphthylene, biphenylene, styrylene, anthrylene, or pyrenylene, which are optionally substituted by C₁-C₁₂alkyl, halogen, —OR²⁰¹, —SR²⁰² and/or —NR²⁰³R²⁰⁴, wherein R²⁰¹ is hydrogen, C₁-C₂₄alkyl, C₁-C₂₄alkyl, which is substituted by E and/or interrupted by D; alkenyl, C₃-C₆alkenoyl, C₃-C₈cycloalkyl, or benzoyl, each of which may optionally be substituted by one or more groups C₁-C₆alkyl, halogen, —OH and/or C₁-C₄alkoxy; C₆-C₁₄aryl, especially phenyl, naphthyl, phenanthryl, anthranyl, or pyrenyl, each of which may optionally be substituted by halogen, —OH, C₁-C₁₂alkyl, C₁-C₁₂alkoxy, phenoxy, C₁-C₁₂alkylsulfanyl, phenylsulfanyl, —N(C₁-C₁₂alkyl)₂ and/or diphenylamino; R²⁰² is C₁-C₂₄alkyl, C₁-C₂₄alkyl, which is substituted by E and/or interrupted by D; C₂-C₁₂alkenyl, C₁-C₈alkanoyl, C₂-C₁₂alkenyl, C₃-C₆alkenoyl; C₃-C₈cycloalkyl, or benzoyl, each of which may optionally be substituted by one or more groups C₁-C₆alkyl, halogen, —OH, C₁-C₄alkoxy or C₁-C₄alkylsulfanyl; C₆-C₁₄aryl, especially phenyl, naphthyl, phenanthryl, anthranyl, or pyrenyl, each of which may optionally be substituted by halogen, C₁-C₁₂alkyl, C₁-C₁₂alkoxy, phenyl-C₁-C₃alkyloxy, phenoxy, C₁-C₁₂alkylsulfanyl, phenylsulfanyl, —N(C₁-C₁₂alkyl)₂, diphenylamino, —(CO)O(C₁-C₈alkyl), —(CO)—C₁-C₈alkyl, or (CO)N(C₁-C₈alkyl)₂; R²⁰³ and R²⁰⁴ are independently of each other hydrogen, C₁-C₂₄alkyl, C₁-C₂₄alkyl, which is substituted by E and/or interrupted by D; C₂-C₅alkenyl, C₃-C₈cycloalkyl, or benzoyl, each of which may optionally be substituted by one or more groups C₁-C₆alkyl, halogen, —OH, or C₁-C₄alkoxy; phenyl-C₁-C₃alkyl, C₁-C₈alkanoyl, C₃-C₁₂alkenoyl, C₆-C₁₄aryl, especially phenyl naphthyl, phenanthryl anthranyl, or pyrenyl, each of which is optionally substituted by C₁-C₁₂alkyl, benzoyl or C₁-C₁₂alkoxy; or R²⁰³ and R²⁰⁴ together are C₂-C₈alkylene, or branched C₂-C₈alkylene optionally interrupted by —O—, —S—, or —NR²⁰⁵— and/or optionally substituted by hydroxyl, C₁-C₄alkoxy, C₂-C₄alkanoyloxy, or benzoyloxy, wherein the ring formed by R²⁰³ and R²⁰⁴ can optionally be condensed one or two times by phenyl which can be substituted one to three times with C₁-C₈-alkyl, C₁-C₈-alkoxy, halogen, or cyano; R²⁰⁵ is hydrogen, C₁-C₂₄alkyl, C₁-C₂₄alkyl, which is substituted by E and/or interrupted by D; C₂-C₅alkenyl, C₃-C₈cycloalkyl, phenyl-C₁-C₃alkyl, C₁-C₈alkanoyl, C₃-C₁₂alkenoyl, C₈-C₁₄aryl, especially benzoyl; phenyl, naphthyl, phenanthryl, anthranyl, or pyrenyl, each of which is optionally substituted by C₁-C₁₂alkyl, benzoyl, or C₁-C₁₂alkoxy; D is —CO—, —COO—, —OCOO—, —S—, —SO—, —SO₂—, —O—, —NR⁵—, —SiR⁶¹R⁶²—, —POR⁵—, —CR⁶³═CR⁶⁴—, or —C≡C—;

E is halogen, C₈-C₁₄aryl, especially phenyl, naphthyl, phenanthryl, anthranyl, or pyrenyl, which may be substituted by —OR⁵, —SR⁵, —NR⁵R⁶, —SiR⁶²R⁶³R⁶⁴, wherein R⁶², R⁶³ and R⁶⁴ are independently of each other a C₁-C₈alkyl group, a C₆-C₂₄aryl group or a C₇-C₁₂aralkyl group, —CN, cyclic ether and/or —B(OR⁶⁵)₂, wherein R⁶⁵ is hydrogen, C₁-C₂₄alkyl, C₃-C₈cycloalkyl, C₇-C₂₄aralkyl, C₂-C₁₈alkenyl, C₂-C₂₄alkynyl, hydroxy, mercapto, C₁-C₂₄alkoxy, C₁-C₂₄alkylthio, C₈-C₃₈aryl, C₂-C₃₈heteroaryl, halogen, especially fluorine, haloalkane, silyl, siloxanyl, and an alicyclic ring formed with adjacent substituents R⁶⁵; —OR⁵, —SR⁵, —NR⁵R⁶, —COR⁸, —COOR⁷, —CONR⁵R⁶, —CN, halogen, silyl, C₁-C₁₈alkyl, or heteroaryl,

G is E, or C₁-C₁₈alkyl, wherein R⁵ and R⁶ are independently of each other H, C₈-C₁₈aryl; C₈-C₁₈aryl which is substituted by C₁-C₁₈alkyl, C₁-C₁₈alkoxy, or silyl; C₁-C₁₈alkyl or C₁-C₁₈alkyl which is interrupted by —O—; or

R⁵ and R⁶ together form a five or six membered ring, in particular

R⁷ is H, C₈-C₁₈aryl, C₇-C₁₂alkylaryl, which are optionally substituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl; or C₁-C₁₈alkyl which is interrupted by —O—; R⁸ is C₈-C₁₈aryl; C₈-C₁₈aryl which is substituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl, C₇-C₁₂alkylaryl, or C₁-C₁₈alkyl which is interrupted by —O—; R⁶¹ and R⁶² are independently of each other C₈-C₁₈aryl; C₈-C₁₈aryl which is substituted by C₁-C₁₈alkyl, C₁-C₁₈alkoxy; or C₁-C₁₈alkyl which is interrupted by —O—, and R⁶³ and R⁶⁴ are independently of each other H, C₈-C₁₈aryl; C₈-C₁₈aryl which is substituted by C₁-C₁₈alkyl, C₁-C₁₈alkoxy; or C₁-C₁₈alkyl which is interrupted by —O—; with the proviso that at least one of R⁸¹, R⁸², R⁸³, R⁸⁴, R⁸⁵, R⁸⁶, R⁸⁷ and R⁸⁸ is different from H, —OR²⁰¹, —SR²⁰² and C₁-C₂₄alkyl; and the further proviso that the following compounds are excluded:

Preferably, the compound or compounds of the present invention emit light below about 520 nm, in particular between about 380 nm and about 520 nm.

The compound or compounds of the present invention have especially a NTSC coordinate of between about (0.12, 0.05) and about (0.16, 0.10), very especially a NTSC coordinate of about (0.14, 0.08).

The compound or compounds of the present invention have a melting point above about 150° C., preferably above about 200° C. and most preferred above about 250° C.

To obtain organic layers of this invention with the proper T_(g), or glass transition temperature, it is advantageous that the present organic compounds have a glass transition temperature greater than about 100° C., for example greater than about 110° C., for example greater than about 120° C., for instance greater than about 130° C.

In one embodiment of the present invention compounds of formula I, or II are preferred, wherein at least one of the groups R⁸¹, R⁸², R⁸³, R⁸⁴, R⁸⁵, R⁸⁶, R⁸⁷, R⁸⁸, R⁹¹, R⁹², R⁹³, R⁹⁴, R⁹⁵, R⁹⁶, R⁹⁷, R^(91′), R^(92′), R^(93′), R^(84′), R^(95′), R^(96′) and R^(97′) is a C₇-C₃₀aryl group, especially a polycyclic C₈-C₃₀aryl group. Compounds of formula I, or II are even more preferred, wherein at least two of the groups R⁸¹, R⁸², R⁸³, R⁸⁴, R⁸⁵, R⁸⁶, R⁸⁷, R⁸⁸, R⁹¹, R⁹², R⁹³, R⁹⁴, R⁹⁵, R⁹⁶, R⁹⁷, R^(91′), R^(92′), R^(93′), R^(94′), R^(95′), R^(96′) and R^(97′) are a C₇-C₃₀aryl group, especially a polycyclic C₈-C₃₀aryl group.

In a further embodiment of the present invention compounds of formula are preferred, wherein M is a single bond, —CO—, —COO—, —S—, —SO—, —SO₂—, —O—,

especially

especially

especially

especially

especially

especially

wherein n1, n2, n3, n4, n5, n6 and n7 are integers of 1 to 10, in particular 1 to 3, A⁶ and A⁷ are independently of each other H, C₁-C₁₈alkyl, C₁-C₁₈alkyl which is substituted by E′ and/or interrupted by D′, C₆-C₂₄aryl, C₆-C₂₄aryl which is substituted by G′, C₂-C₂₀heteroaryl, C₂-C₂₀heteroaryl which is substituted by G′, C₂-C₁₈alkenyl, C₂-C₁₈alkynyl, C₁-C₁₈alkoxy, C₁-C₁₈alkoxy which is substituted by E′ and/or interrupted by D′, C₇-C₂₅aralkyl, or —CO-A²⁸, A⁸ is C₁-C₁₈alkyl, C₁-C₁₈alkyl which is substituted by E′ and/or interrupted by D′, C₆-C₂₄ aryl, or C₇-C₂₅aralkyl, A⁹ and A¹⁰ are independently of each other C₁-C₁₈alkyl, C₁-C₁₈alkyl which is substituted by E′ and/or interrupted by D′, C₆-C₂₄aryl, C₆-C₂₄aryl which is substituted by G′, C₂-C₂₀heteroaryl, C₂-C₂₀heteroaryl which is substituted by G′, C₂-C₁₈alkenyl, C₂-C₁₈alkynyl, C₁-C₁₈alkoxy, C₁-C₁₈alkoxy which is substituted by E′ and/or interrupted by D′, or C₇-C₂₅aralkyl, or A⁹ and A¹⁰ form a ring, especially a five- or six-membered ring, which can optionally be substituted by one or more C₁-C₁₈ alkyl groups; A¹⁴ and A¹⁵ are independently of each other H, C₁-C₁₈alkyl, C₁-C₁₈alkyl which is substituted by E′ and/or interrupted by D′, C₆-C₂₄aryl, C₆-C₂₄aryl which is substituted by G′, C₂-C₂₀heteroaryl, or C₂-C₂₀heteroaryl which is substituted by G′, D′ is —CO—; —COO—; —S—; —SO—; —SO₂—; —O—; —NA²⁵-; —SiA³⁰A³¹-; —POA³²-; —CA²³=CA²⁴-; or —C≡C—; and E′ is —OA²⁹; —SA²⁹; —NA²⁵A²⁶; —COA²⁸; —COOA²⁷; —CONA²⁶A²⁶; —CN; —OCOOA²⁷; or halogen; G′ is E′, or C₁-C₁₈alkyl; wherein A²³, A²⁴, A²⁵ and A²⁶ are independently of each other H; C₆-C₁₈aryl; C₆-C₁₈aryl which is substituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl, or C₁-C₁₈alkyl which is interrupted by —O—; or A²⁵ and A²⁶ together form a five or six membered ring, in particular

A²⁷ and A²⁸ are independently of each other H; C₆-C₁₈aryl; C₆-C₁₈aryl which is substituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl, or C₁-C₁₈alkyl which is interrupted by —O—, A²⁹ is H; C₆-C₁₈aryl; C₆-C₁₈aryl, which is substituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl; or C₁-C₁₈alkyl which is interrupted by —O—, A³⁰ and A³¹ are independently of each other C₁-C₁₈alkyl, C₆-C₁₈aryl, or C₆-C₁₈aryl, which is substituted by C₁-C₁₈alkyl, and A³² is C₁-C₁₈alkyl, C₆-C₁₈aryl, or C₆-C₁₈aryl, which is substituted by C₁-C₁₈alkyl.

Preferably, A⁶ and A⁷ are independently of each other H, C₁-C₁₈alkyl, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, isobutyl, sec-butyl, t-butyl, 2-methylbutyl, n-pentyl, isopentyl, n-hexyl, 2-ethylhexyl, or n-heptyl, C₁-C₁₈alkyl which is substituted by E′ and/or interrupted by D′, such as —CH₂OCH₃, —CH₂OCH₂CH₃, —CH₂OCH₂CH₂OCH₃, or —CH₂OCH₂CH₂OCH₂CH₃, C₆-C₂₄aryl, such as phenyl, naphthyl, or biphenyl, C₆-C₂₄aryl which is substituted by G′, such as —C₆H₄OCH₃, —C₆H₄OCH₂CH₃, —C₆H₃(OCH₃)₂, or —C₆H₃(OCH₂CH₃)₂, —C₆H₄CH₃, —C₆H₃(CH₃)₂, —C₆H₂(CH₃)₃, or —C₆H₄tBu.

A⁸ is preferably H, C₁-C₁₈alkyl, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, isobutyl, sec-butyl, t-butyl, 2-methylbutyl, n-pentyl, isopentyl, n-hexyl, 2-ethylhexyl, n-heptyl, or C₆-C₂₄aryl, such as phenyl, naphthyl, or biphenyl.

Preferably, A⁹ and A¹⁰ are independently of each other H, C₁-C₁₈alkyl, such as n-butyl, sec-butyl, hexyl, octyl, or 2-ethyl-hexyl, C₁-C₁₈alkyl which is substituted by E′ and/or interrupted by D′, such as —CH₂(OCH₂CH₂)_(w)OCH₃, w=1, 2, 3, or 4, C₆-C₂₄aryl, such as phenyl, naphthyl, or biphenyl, C₆-C₂₄aryl which is substituted by G′, such as —C₆H₄OCH₃, —C₆H₄OCH₂CH₃, —C₆H₃(OCH₃)₂, —C₆H₃(OCH₂CH₃)₂, —C₆H₄CH₃, —C₆H₃(CH₃)₂, —C₆H₂(CH₃)₃, or —C₆H₄tBu, or A⁹ and A¹⁰ together form a 4 to 8 membered ring, especially a 5 or 6 membered ring, such as cyclohexyl, or cyclopentyl.

Preferably, A¹⁴ and A¹⁵ are independently of each other H, C₁-C₁₈alkyl, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, isobutyl, or sec-butyl, or C₆-C₂₄aryl, such as phenyl, naphthyl, or biphenyl.

D′ is preferably —CO—, —COO—, —S—, —SO—, —SO₂—, —O—, —NA²⁵-, wherein A²⁵ is C₁-C₁₈alkyl, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, isobutyl, or sec-butyl, or C₆-C₂₄aryl, such as phenyl, naphthyl, or biphenyl.

E′ is preferably —OA²⁹; —SA²⁹; —NA²⁵A²⁵; —COA²⁸; —COOA²⁷; —CONA²⁵A²⁵; or —CN; wherein A²⁵, A²⁷, A²⁸ and A²⁹ are independently of each other C₁-C₁₈alkyl, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, isobutyl, sec-butyl, hexyl, octyl, or 2-ethyl-hexyl, or C₆-C₂₄ aryl, such as phenyl, naphthyl, or biphenyl.

Among the above-mentioned groups M the following groups are preferred:

Examples of especially preferred groups M are:

wherein A⁸ and A⁹ are independently of each other C₁-C₁₈alkyl, or cyclohexan;

wherein A⁶ and A⁷ are independently of each other H, or C₁-C₁₈alkyl; or

Groups M having a polycyclic C₈-C₃₀arylen group, or a polycyclic C₄-C₂₆heteroarylen group, wherein polycyclic ring system comprises at least 8 atoms, are preferred,

are most preferred.

Among the compounds of formula II compounds of formula

are preferred.

Compounds of formula

are even more preferred, wherein R⁹⁵ and R^(95′) are independently of each other C₁-C₂₄alkyl, or C₆-C₁₈aryl, especially phenyl, naphthyl, phenanthryl, anthranyl, or pyrenyl, which may be substituted by one, or more C₁-C₈alkyl, or C₁-C₈alkoxy groups, such as a group of formula

especially

wherein R⁴¹, R^(41′), R⁴² and R^(42′) are independently of each other is hydrogen, C₁-C₈alkyl, or C₁-C₈alkoxy, R^(45′) is hydrogen, phenyl, or 1-naphthyl, which can be substituted by one, or more C₁-C₈alkyl, or C₁-C₈alkoxy groups; or C₁-C₈alkyl, or C₁-C₈alkoxy.

In another embodiment compounds of formula IIb are preferred, wherein M is a single bond,

R⁹⁶ and R^(96′) are a group

especially

and R⁹¹, R⁹², R⁹³, R⁹⁴, R⁹⁵, R⁹⁶, R⁹⁷, R^(91′), R^(92′), R^(93′), R^(94′), R^(95′), R^(96′) and R^(97′) are hydrogen.

Examples of especially preferred compounds are:

In further preferred embodiment of the present invention at least one, preferably two of the groups R⁸¹, R⁸², R⁸³, R⁸⁴, R⁸⁵, R⁸⁶, R⁸⁷, R⁸⁸, R⁹¹, R⁹², R⁹³, R⁹⁴, R⁹⁵, R⁹⁶, R⁹⁷, R^(91′), R^(92′), R^(93′), R^(94′), R^(95′), R^(96′) and R^(97′) are a group

wherein A^(14′) and A^(15′) are independently of each other H, C₁-C₁₈alkyl, C₁-C₁₈alkyl which is substituted by E and/or interrupted by D, C₆-C₂₄aryl, C₆-C₂₄aryl which is substituted by G, C₂-C₂₀heteroaryl, or C₂-C₂₀heteroaryl which is substituted by G, and A^(16′) is H, C₁-C₁₈alkyl, C₁-C₁₈alkyl which is substituted by E and/or interrupted by D, C₆-C₂₄aryl, C₆-C₂₄aryl which is substituted by G, C₂-C₂₀heteroaryl, or C₂-C₂₀heteroaryl which is substituted by G; or a polycyclic aryl group, especially pentalenyl, indenyl, azulenyl, naphthyl, biphenylenyl, as-indacenyl, s-indacenyl, acenaphthylenyl, fluorenyl, phenanthryl, anthracenyl, fluoranthenyl, acephenanthrylenyl, aceanthrylenyl, triphenylenyl, pyrenyl, chrysenyl, naphthacenyl, picenyl, perylenyl, pentacenyl, pentaphenyl, hexacenyl, or hexaphenyl, which can optionally be substituted by G, wherein D, E and G are as defined above.

Examples of particularly preferred groups are:

wherein R³⁰⁰ is C₁-C₈alkyl, phenyl, which can be substituted by one, or more C₁-C₈alkyl, or C₁-C₈alkoxy groups, R¹⁴ is hydrogen, C₁-C₈alkyl, phenyl, or 1-naphthyl, which can be substituted by one, or more C₁-C₈alkyl, or C₁-C₈alkoxy groups; or C₁-C₈alkoxy, and R¹⁸ and R¹⁹ are independently of each other C₁-C₈alkyl, or cyclohexan.

Compounds of formula Ia, Ib and Ic are preferred, wherein R⁸², R⁸⁷, R⁸³, R⁸⁸, R^(83′) and R^(86′) are independently of each other one of the above groups. R⁸² and R⁸⁷, R⁸³ and R⁸⁶, R^(83′) and R^(86′) can be the same or different.

In a further preferred embodiment of the present invention at least one, especially two of the groups R⁸¹, R⁸², R⁸³, R⁸⁴, R⁸⁵, R⁸⁶, R⁸⁷, R⁸⁸, R⁹¹, R⁹², R⁹³, R⁹⁴, R⁹⁵, R⁹⁶, R⁹⁷, R^(91′), R^(92′), R^(93′), R^(94′), R^(95′), R^(98′) and R^(97′) are independently of each other a group the formula —(W¹)_(a)—(W²)_(b)—W³(Y¹), wherein

a and b are 0, or 1,

W¹ and W² are independently of each other a group of formula

especially

and W³ is a group of formula

especially

wherein R¹¹, R^(11′), R¹², R^(12′), R¹³, R^(13′), R¹⁵, R^(15′), R¹⁶, R^(16′), R¹⁷, R^(17′), R⁴¹, R^(41′), R⁴², R^(42′), R⁴⁴, R^(44′), R⁴⁵, R^(45′), R⁴⁶, R^(46′), R⁴⁷ and R^(47′) are independently of each other H, E, silyl, such as tri(C₁-C₈alkyl)silyl, C₆-C₁₈aryl; C₆-C₁₈aryl which is substituted by G; C₁-C₁₈alkyl; C₁-C₁₈alkyl which is substituted by E and/or interrupted by D; C₁-C₁₈alkoxy; or C₁-C₁₈alkoxy which is substituted by E and/or interrupted by D; C₇-C₁₈aralkyl; or C₇-C₁₈aralkyl which is substituted by G; R¹⁴ is H, silyl, such as tri(C₁-C₈alkyl)silyl, C₁-C₁₈alkyl; or C₁-C₁₈alkyl which is substituted by E and/or interrupted by D; C₁-C₁₈alkoxy; or C₁-C₁₈alkoxy which is substituted by E and/or interrupted by D;

R¹⁸ and R¹⁹ are independently of each other C₁-C₁₈alkyl; C₁-C₁₈alkoxy, C₆-C₁₈aryl; C₇-C₁₈aralkyl; or R¹⁸ and R¹⁹ together form a ring especially a five- or six-membered ring, which can optionally be substituted by C₁-C₈alkyl, R²¹, R²², R²³, R²⁴, R²⁵, R²⁶ and R²⁷ are independently of each other H, E, C₁-C₁₈alkyl; C₁-C₁₈alkyl which is substituted by E and/or interrupted by D; C₇-C₁₈aralkyl; C₇-C₁₈aralkyl which is substituted by G; or W³ is a group of formula

wherein R³¹⁵ and R³¹⁶ are independently of each other a hydrogen atom, a C₁-C₁₈alkyl group, a C₁-C₁₈alkoxy group, a group of formula

wherein R³¹⁸, R³¹⁹ and R³²⁰ independently from each other stand for hydrogen, C₁-C₈-alkyl, C₁-C₈-alkoxy, or phenyl, and R³¹⁷ stands for is a hydrogen atom, a C₁-C₂₅alkyl group, which might be interrupted by —O—, a cycloalkyl group, a C₇-C₁₈aralkyl group, a C₆-C₁₈aryl group, or a heterocyclic group, which may be substituted by G; wherein D is —CO—, —COO—, —OCOO—, —S—, —SO—, —SO₂—, —O—, —NR⁸—, SiR⁶¹R⁶²—, —POR⁵—, —CR⁶³═CR⁶⁴—, or —C≡C—; E is —OR⁵, —SR⁵, —NR⁵R⁶, —COR⁸, —COOR⁷, —OCOOR⁷, —CONR⁵R⁶, —CN, or halogen; G is E, or C₁-C₁₈alkyl; wherein R⁵ and R⁶ are independently of each other C₆-C₁₈aryl; C₆-C₁₈aryl which is substituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl, or C₁-C₁₈alkyl which is interrupted by —O—; or R⁵ and R⁶ together form a five or six membered ring, in particular

R⁷ is C₇-C₁₂alkylaryl; C₁-C₁₈alkyl; or C₁-C₁₈alkyl which is interrupted by —O—; R⁸ is C₆-C₁₈aryl; C₆-C₁₈aryl which is substituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl; C₇-C₁₂alkylaryl, or C₁-C₁₈alkyl which is interrupted by —O—; R⁶¹ and R⁶² are independently of each other C₆-C₁₈aryl; C₆-C₁₈aryl which is substituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; or C₁-C₁₈alkyl which is interrupted by —O—, and R⁶³ and R⁶⁴ are independently of each other H, C₆-C₁₈aryl; C₆-C₁₈aryl which is substituted by C₁-C₁₈alkyl, C₁-C₁₈alkoxy; or C₁-C₁₈alkyl which is interrupted by —O—.

If W³ is derived from a heteroaromatic group, it is preferably a group of formula

wherein R³¹⁷ is C₁-C₁₈alkyl.

Examples of preferred groups W¹ and W² are

wherein R¹¹ is hydrogen, or C₁-C₈alkyl.

Examples of preferred groups W³ are

wherein R¹⁴, R^(41′) and R⁴⁴ are hydrogen, phenyl, tri(C₁-C₈alkyl)silyl, or C₁-C₈alkyl, R¹⁸ and R¹⁹ are independently of each other C₁-C₈alkyl, or cyclohexan.

Examples of preferred groups —(W¹)_(a)—(W²)_(b)—W³ are

wherein R¹¹, R¹⁴, R¹⁸ and R¹⁹ are independently of each other hydrogen, or C₁-C₈alkyl.

Among the compounds of formula I compounds of formula

are more preferred, wherein R⁸², R⁸³, R⁸⁶ and R⁸⁷ are independently of each other a group the formula —(W¹)_(a)—(W²)_(b)—W³. R⁸², R⁸³, R⁸⁶ and R⁸⁷ can be different, but are preferably the same; and R⁸¹ and R⁸⁸ are as defined above.

In a preferred embodiment of the present invention at least one, preferably two of the substituents R⁸², R⁸³, R⁸⁶, R⁸⁷, R⁸¹ and R⁸⁸ are

especially

Compounds of formula Ia are even more preferred, wherein R⁸³ and R⁸⁶ are

especially

In a further preferred embodiment of the present invention compounds of formula

are preferred, wherein R⁸¹, R⁸³ and R⁸³ a group the formula —(W²)—W³, wherein W² is a group

wherein R^(13′) and R¹⁷ are independently of each other C₁-C₁₈alkyl, or C₁-C₁₈alkoxy,

W³ is a group

A further preferred embodiment of the present invention is directed to compounds of formula Ia and Ib, wherein at least R⁸² and at least R⁸³ are a group of formula

wherein A^(14′) and A^(15′) are independently of each other H, C₁-C₁₈alkyl, C₆-C₂₄aryl, or phenyl, which is substituted by one, or more C₁-C₈alkyl, or C₁-C₈alkoxy groups and the other, and R⁸⁷ and R⁸⁶ are a group of formula

or a group of formula —(W¹)_(a)—(W²)_(b)—W³.

A further preferred embodiment of the present invention is directed to compounds of formula

wherein R^(83′) and R^(86′) are independently of each other H, C₁-C₁₈alkyl,

wherein R¹⁴ is hydrogen, phenyl, tri(C₁-C₈alkyl)silyl, or C₁-C₈alkyl, R¹⁸ and R¹⁹ are independently of each other C₁-C₈alkyl, or cyclohexan.

Examples of especially preferred compounds are given below:

Particularly suitable dibenzo-, dinaphthofurans are compounds A-1, A-2, A-4, A-5, A-10, A-11, A-16, A-19, B-1 and B-2.

In another preferred embodiment at least one, preferably two of the substituents R⁸¹, R⁸², R⁸³, R⁸⁴, R⁸⁵, R⁸⁶, R⁸⁷, R⁸⁸, R⁹¹, R⁹², R⁹³, R⁹⁴, R⁹⁵, R⁹⁶, R⁹⁷, R^(91′), R^(92′), R^(93′), R^(94′), R^(95′), R^(96′) and R^(97′) are independently of each other a group of the formula —W¹—(W²)_(b)—W³(Y²), wherein b is 0, or, 1, W¹ and W² are as defined above and are preferably independently of each other a group of formula

especially

W³ is a group of formula —NR⁷⁰R⁷¹, wherein R⁷⁰ and R⁷¹ are independently of each other a group of formula

wherein R⁷², R⁷³ and R⁷⁴ are independently of each other hydrogen, C₁-C₈alkyl, a hydroxyl group, a mercapto group, C₁-C₈alkoxy, C₁-C₈alkylthio, halogen, halo-C₁-C₈alkyl, a cyano group, an aldehyde group, a ketone group, a carboxyl group, an ester group, a carbamoyl group, an amino group, a nitro group, a silyl group or a siloxanyl group, or R⁷⁰ and R⁷¹ together with the nitrogen atom to which they are bonded form a five or six membered heterocyclic ring, such as

which can be condensed by one or two optionally substituted phenyl groups, such as

wherein R²¹⁶ and R²¹⁷ independently from each other stands for hydrogen, C₁-C₈alkyl, C₁-C₈alkoxy, or phenyl, and X¹ stands for hydrogen, or C₁-C₈alkyl; R⁷⁵, R⁷⁶, R⁷⁷ and R⁷⁸ are independently of each other H, E, C₆-C₁₈aryl; C₆-C₁₈aryl which is substituted by E; C₁-C₁₈alkyl; C₁-C₁₈alkyl which is substituted by G and/or interrupted by D; C₇-C₁₈aralkyl; or C₇-C₁₈aralkyl which is substituted by E; wherein D, E, G, R¹¹, R^(11′), R^(12′), R¹⁶, R^(16′), R¹⁷, R^(17′), R¹⁸, R¹⁹, R³⁰, R³¹, R³² and R³³ are as defined above, and R^(30′), R^(31′), R^(32′) and R^(33′) independently of each other have the meaning of R³⁰.

If R⁷⁰ and R⁷¹ are independently of each other a group of formula

b is preferably 1.

In said embodiment groups of the formula —W¹—(W²)_(b)—W³ are more preferred, wherein b is 0, or 1,

W¹ and W² are independently of each other a group of formula

W³ is a group of formula

or —NR⁷⁰R⁷¹, wherein R⁷⁰ and R⁷¹ are independently of each other a group of formula

wherein R⁷² is C₁₋₁₈alkyl.

In said embodiment of the present invention compounds of formula Ia and Ib are preferred, wherein R⁸² and R⁸⁷ and R⁸³ and R⁸⁶ are independently of each other a group of formula —(W²)_(b)—W³. The groups —(W²)_(b)—W³ can be different, but are preferably the same.

Examples of preferred compounds are given below:

In another preferred embodiment the present invention is directed to compounds of formula I wherein at least one of R⁸¹, R⁸², R⁸³, R⁸⁴, R⁸⁵, R⁸⁶, R⁸⁷ and R⁸⁸ is a group Y¹ and at least one of R⁸¹, R⁸², R⁸³, R⁸⁴, R⁸⁵, R⁸⁶, R⁸⁷ and R⁸⁸ is a group Y².

In said embodiment compounds of formula Ia are preferred, wherein R⁸¹ is H, R⁸⁸ is Y² and R⁸³ and R⁸⁶ are Y¹; or R⁸¹ and R⁸⁸ are H, R⁸³ is Y² and R⁸⁶ are Y¹.

Examples of preferred compounds are given below:

The present benzofuran compounds show a high solid state fluorescence in the desired wavelength range and can be prepared according to or analogous to known procedures (see, for example, WO99/47474, WO2004039786 and WO2004077885).

The benzofuran compounds of the present invention of the formula:

wherein W³ is as defined above, can, for example, be prepared according to a process, which comprises reacting a derivative of formula

wherein R¹⁰⁰ stands for halogen such as chloro or bromo, preferably bromo, or E having the meaning of

wherein a is 2 or 3, with boronic acid derivative E-W³, or—in case R¹⁰⁰ is not halogen -Hal-W³, wherein Hal stands for halogen, preferably for bromo, in the presence of an allylpalladium catalyst of the μ-halo(triisopropylphosphine)(η³-allyl)palladium(II) type (see for example WO99/47474).

Preferably, the reaction is carried out in the presence of an organic solvent, such as an aromatic hydrocarbon or a usual polar organic solvent, such as benzene, toluene, xylene, tetrahydrofurane, or dioxane, or mixtures thereof, most preferred toluene. Usually, the amount of the solvent is chosen in the range of from 1 to 10 l per mol of boronic acid derivative. Also preferred, the reaction is carried out under an inert atmosphere such as nitrogen, or argon.

Further, it is preferred to carry out the reaction in the presence of an aqueous base, such as an alkali metal hydroxide or carbonate such as NaOH, KOH, Na₂CO₃, K₂CO₃, Cs₂CO₃ and the like, preferably an aqueous K₂CO₃ solution is chosen. Usually, the molar ratio of the base to compound III is chosen in the range of from 0.5:1 to 50:1.

Generally, the reaction temperature is chosen in the range of from 40 to 180° C., preferably under reflux conditions.

Preferred, the reaction time is chosen in the range of from 1 to 80 hours, more preferably from 20 to 72 hours.

In a preferred embodiment a usual catalyst for coupling reactions or for polycondensation reactions is used, preferably Pd-based catalyst such as known tetrakis(triarylphosphonium)-palladium, preferably (Ph₃P)₄Pd and derivatives thereof. Usually, the catalyst is added in a molar ratio from inventive DPP polymer to the catalyst in the range of from 100:1 to 10:1, preferably from 50:1 to 30:1.

Also preferred, the catalyst is added as in solution or suspension. Preferably, an appropriate organic solvent such as the ones described above, preferably benzene, toluene, xylene, THF, dioxane, more preferably toluene, or mixtures thereof, is used. The amount of solvent usually is chosen in the range of from 1 to 10 l per mol of boronic acid derivative.

The obtained inventive polymer can be isolated by well-known methods. Preferably, after cooling down the reaction mixture to room temperature, it is poured into acetone and the obtained precipitation is filtered off, washed and dried.

C₁-C₁₈Alkyl is a branched or unbranched radical such as for example methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethyl-butyl, n-hexyl, 1-methylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methyl-heptyl, n-octyl, 2-ethylhexyl, 1,1,3-trimethylhexyl, 1,1,3,3-tetramethylpentyl, nonyl, decyl, undecyl, 1-methylundecyl, dodecyl, 1,1,3,3,5,5-hexamethylhexyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, or octadecyl.

C₁-C₁₈Alkoxy radicals are straight-chain or branched alkoxy radicals, e.g. methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, amyloxy, isoamyloxy or tert-amyloxy, heptyloxy, octyloxy, isooctyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tetradecyloxy, pentadecyloxy, hexadecyloxy, heptadecyloxy and octadecyloxy.

C₂-C₁₈Alkenyl radicals are straight-chain or branched alkenyl radicals, such as e.g. vinyl, allyl, methallyl, isopropenyl, 2-butenyl, 3-butenyl, isobutenyl, n-penta-2,4-dienyl, 3-methyl-but-2-enyl, n-oct-2-enyl, n-dodec-2-enyl, isododecenyl, n-dodec-2-enyl or n-octadec-4-enyl.

C₂₋₂₄Alkynyl is straight-chain or branched and preferably C₂₋₈alkynyl, which may be unsubstituted or substituted, such as, for example, ethynyl, 1-propyn-3-yl, 1-butyn-4-yl, 1-pentyn-5-yl, 2-methyl-3-butyn-2-yl, 1,4-pentadiyn-3-yl, 1,3-pentadiyn-5-yl, 1-hexyn-6-yl, cis-3-methyl-2-penten-4-yn-1-yl, trans-3-methyl-2-penten-4-yn-1-yl, 1,3-hexadiyn-5-yl, 1-octyn-8-yl, 1-nonyn-9-yl, 1-decyn-10-yl or 1-tetracosyn-24-yl.

C₄-C₁₈cycloalkyl is preferably C₅-C₁₂cycloalkyl, such as, for example, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cyclododecyl. Cyclohexyl and cyclododecyl are most preferred.

The term “aryl group” is typically C₆-C₃₀aryl, such as phenyl, indenyl, azulenyl, naphthyl, biphenyl, terphenylyl or quadphenylyl, as-indacenyl, s-indacenyl, acenaphthylenyl, phenanthryl, fluoranthenyl, triphenlenyl, chrysenyl, naphthacen, picenyl, perylenyl, pentaphenyl, hexacenyl, pyrenyl, or anthracenyl, preferably phenyl, 1-naphthyl, 2-naphthyl, 9-phenanthryl, 2- or 9-fluorenyl, 3- or 4-biphenyl, which may be unsubstituted or substituted. Examples of C₆-C₁₈aryl are phenyl, 1-naphthyl, 2-naphthyl, 3- or 4-biphenyl, 9-phenanthryl, 2- or 9-fluorenyl, which may be unsubstituted or substituted.

C₇-C₂₄aralkyl radicals are preferably C₇-C₁₈aralkyl radicals, which may be substituted, such as, for example, benzyl, 2-benzyl-2-propyl, β-phenyl-ethyl, α,α-dimethylbenzyl, ω-phenyl-butyl, ω,ω-dimethyl-ω-phenyl-butyl, ω-phenyl-dodecyl, ω-phenyl-octadecyl, ω-phenyl-eicosyl or ω-phenyl-docosyl, preferably C₇-C₁₈aralkyl such as benzyl, 2-benzyl-2-propyl, β-phenyl-ethyl, α,α-dimethylbenzyl, ω-phenyl-butyl, ω,ω-dimethyl-ω-phenyl-butyl, ω-phenyl-dodecyl or ω-phenyl-octadecyl, and particularly preferred C₇-C₁₂aralkyl such as benzyl, 2-benzyl-2-propyl, β-phenyl-ethyl, α,α-dimethylbenzyl, ω-phenyl-butyl, or ω,ω-dimethyl-ω-phenyl-butyl, in which both the aliphatic hydrocarbon group and aromatic hydrocarbon group may be unsubstituted or substituted.

C₇-C₁₂alkylaryl is, for example, a phenyl group substituted with one, two or three C₁-C₆alkyl groups, such as, for example, 2-, 3-, or 4-methylphenyl, 2-, 3-, or 4-ethylphenyl, 3-, or 4-isopropylphenyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl, or 3,4,5-trimethylphenyl.

The term “heteroaryl group”, especially C₂-C₃₀heteroaryl, is a ring, wherein nitrogen, oxygen or sulfur are the possible hetero atoms, and is typically an unsaturated heterocyclic radical with five to 18 atoms having at least six conjugated π-electrons such as thienyl, benzo[b]thienyl, dibenzo[b,d]thienyl, thianthrenyl, furyl, furfuryl, 2H-pyranyl, benzofuranyl, isobenzofuranyl, 2H-chromenyl, xanthenyl, dibenzofuranyl, phenoxythienyl, pyrrolyl, imidazolyl, pyrazolyl, pyridyl, bipyridyl, triazinyl, pyrimidinyl, pyrazinyl, 1H-pyrrolizinyl, isoindolyl, pyridazinyl, indolizinyl, isoindolyl, indolyl, 3H-indolyl, phthalazinyl, naphthyridinyl, quinoxalinyl, quinazolinyl, cinnolinyl, indazolyl, purinyl, quinolizinyl, chinolyl, isochinolyl, phthalazinyl, naphthyridinyl, chinoxalinyl, chinazolinyl, cinnolinyl, pteridinyl, carbazolyl, 4aH-carbazolyl, carbolinyl, benzotriazolyl, benzoxazolyl, phenanthridinyl, acridinyl, perimidinyl, phenanthrolinyl, phenazinyl, isothiazolyl, phenothiazinyl, isoxazolyl, furazanyl or phenoxazinyl, preferably the above-mentioned mono- or bicyclic heterocyclic radicals, which may be unsubstituted or substituted.

Halogen is fluorine, chlorine, bromine and iodine.

The terms “haloalkyl” mean groups given by partially or wholly substituting the above-mentioned alkyl group, with halogen, such as trifluoromethyl etc. The “aldehyde group, ketone group, ester group, carbamoyl group and amino group” include those substituted by an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or a heterocyclic group, wherein the alkyl group, the cycloalkyl group, the aryl group, the aralkyl group and the heterocyclic group may be unsubstituted or substituted. The term “silyl group” means a group of formula —SiR⁶²R⁶³R⁶⁴, wherein R⁶², R⁶³ and R⁶⁴ are independently of each other a C₁-C₈alkyl group, in particular a C₁-C₄alkyl group, a C₆-C₂₄aryl group or a C₇-C₁₂aralkyl group, such as a trimethylsilyl group. The term “siloxanyl group” means a group of formula —O—SiR⁶²R⁶³R⁶⁴, wherein R⁶², R⁶³ and R⁶⁴ are as defined above, such as a trimethylsiloxanyl group.

Possible substituents of the above-mentioned groups are C₁-C₈alkyl, a hydroxyl group, a mercapto group, C₁-C₈alkoxy, C₁-C₈alkylthio, halogen, halo-C₁-C₈alkyl, a cyano group, an aldehyde group, a ketone group, a carboxyl group, an ester group, a carbamoyl group, an amino group, a nitro group or a silyl group.

As described above, the aforementioned radicals may be substituted by E and/or, if desired, interrupted by D. Interruptions are of course possible only in the case of radicals containing at least 2 carbon atoms connected to one another by single bonds; C₆-C₁₈aryl is not interrupted; interrupted arylalkyl or alkylaryl contains the unit D in the alkyl moiety. C₁-C₁₈alkyl substituted by one or more E and/or interrupted by one or more units D is, for example, (CH₂CH₂O)_(n)—R^(x), where n′ is a number from the range 1-9 and R^(x) is H or C₁-C₁₀alkyl or C₂-C₁₀alkanoyl (e.g. CO—CH(C₂H₅)C₄H₉), CH₂—CH(OR^(y′))—CH₂—O—R^(y), where R^(y) is C₁-C₁₈alkyl, C₅-C₁₂cycloalkyl, phenyl, C₇-C₁₅-phenylalkyl, and R^(y′) embraces the same definitions as R^(y) or is H; C₁-C₈alkylene-COO—R^(z), e.g. CH₂COOR^(z), CH(CH₃)COOR^(z), C(CH₃)₂COOR^(z), where R^(z) is H, C₁-C₁₈alkyl, (CH₂CH₂O)₁₋₉—R^(x), and R^(x) embraces the definitions indicated above;

CH₂CH₂—O—CO—CH═CH₂; CH₂CH(OH)CH₂—O—CO—C(CH₃)═CH₂.

The electroluminescent devices may be employed for full color display panels in, for example, mobile phones, televisions and personal computer screens.

The electroluminescent devices of the present invention are otherwise designed as is known in the art, for example as described in U.S. Pat. Nos. 5,518,824, 6,225,467, 6,280,859, 5,629,389, 5,486,406, 5,104,740, 5,116,708 and 6,057,048, the relevant disclosures of which are hereby incorporated by reference.

For example, organic EL devices contain one or more layers such as:

substrate; base electrode; hole-injecting layer; hole transporting layer; emitter layer; electron-transporting layer; electron-injecting layer; top electrode; contacts and encapsulation.

This structure is a general case and may have additional layers or may be simplified by omitting layers so that one layer performs a plurality of tasks. For instance, the simplest organic EL device consists of two electrodes which sandwich an organic layer that performs all functions, including the function of light emission.

A preferred EL device comprises in this order:

(a) an anode,

(b) a hole injecting layer and/or a hole transporting layer,

(c) a light-emitting layer,

(d) optionally an electron transporting layer and

(e) a cathode.

The benzofuran compounds of the present invention can, in principal be used for any organic layer, such as, for example, hole transporting layer, light emitting layer, or electron transporting layer, but are preferably used as the light emitting material in the light emitting layer, optionally as a host or guest component, or electron transporting layer.

In particular, the present organic compounds function as light emitters and are contained in the light emission layer or form the light-emitting layer.

The light emitting compounds of this invention exhibit intense fluorescence in the solid state and have excellent electric-field-applied light emission characteristics. Further, the light emitting compounds of this invention are excellent in the injection of holes from a metal electrode and the transportation of holes; as well as being excellent in the injection of electrons from a metal electrode and the transportation of electrons. They are effectively used as light emitting materials and may be used in combination with other hole transporting materials, other electron transporting materials or other dopants.

The organic compounds of the present invention form uniform thin films. The light emitting layers may therefore be formed of the present organic compounds alone.

Alternatively, the light-emitting layer may contain a known light-emitting material, a known dopant, a known hole transporting material or a known electron transporting material as required. In the organic EL device, a decrease in the brightness and life caused by quenching can be prevented by forming it as a multi-layered structure. The light-emitting material, a dopant, a hole-injecting material and an electron-injecting material may be used in combination as required. Further, a dopant can improve the light emission brightness and the light emission efficiency, and can attain the red or blue light emission. Further, each of the hole transporting zone, the light-emitting layer and the electron transporting zone may have the layer structure of at least two layers. In the hole transporting zone in this case, a layer to which holes are injected from an electrode is called “hole-injecting layer”, and a layer which receives holes from the hole-injecting layer and transport the holes to a light-emitting layer is called “hole transporting layer”. In the electron transporting zone, a layer to which electrons are injected from an electrode is called “electron-injecting layer”, and a layer which receives electrons from the electron-injecting layer and transports the electrons to a light-emitting layer is called “electron transporting layer”. These layers are selected and used depending upon factors such as the energy level and heat resistance of materials and adhesion to an organic layer or metal electrode.

The light-emitting material or the dopant which may be used in the light-emitting layer together with the organic compounds of the present invention includes for example anthracene, naphthalene, phenanthrene, pyrene, tetracene, coronene, chrysene, fluorescein, perylene, phthaloperylene, naphthaloperylene, perinone, phthaloperinone, naphthaloperinone, diphenylbutadiene, tetraphenylbutadiene, coumarine, oxadiazole, aldazine, bisbenzoxazoline, bisstyryl, pyrazine, cyclopentadiene, quinoline metal complex, aminoquinoline metal complex, benzoquinoline metal complex, imine, diphenylethylene, vinyl anthracene, diaminocarbazole, pyran, thiopyran, polymethine, merocyanine, an imidazole-chelated oxynoid compound, quinacridone, rubrene, and fluorescent dyestuffs for a dyestuff laser or for brightening.

It is also possible to use the compounds of the present invention with phosphorescent materials as a dopant in the light-emitting layer. Examples of the phosphorescent materials are, for example, metal complexes of Ir, Pt, Eu, Ru, Rh, Pd, Ag, Re, Os and Au and are described, for example, in JP2005-11804 and WO2004/034751.

Examples of typical structures of the metal complex are shown below:

In that case the electroluminescent device may comprise in this order

(a) an anode, such as, for example, ITO,

(b1) a hole injecting layer, such as, for example, CuPc,

(b2) a hole transporting layer, such as, for example, such as, for example, N,N′-Di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPD), or TCTA,

(c) a light-emitting layer, comprising a phosphorescent compound and a dibenzofuran compound of the present invention, especially a compound A-1 to A-66, B-1 to B-18, C-1 and C-2.

a positive hole inhibiting layer, such as, for example, BCP, or BAlq,

(d) an electron transporting layer, such as, for example, Alq₃, and

an inorganic compound layer, such as, for example, LiF,

(e) a cathode, such as, for example, Al.

If the dibenzofuran compounds of the present invention are used as host together with guest compounds, such, as for example, 2,5,8,11-tetra-t-butylperylene (Jiaumin Shi Ching W. Tang, Appl. Phys. Lett. 80, 3201 (2002), or the compounds, described, for example, in WO03/105538, such as, for example,

the electroluminescent device may comprise in this order (a) an anode, such as, for example, ITO, (b1) a hole injecting layer, such as, for example, CuPc, (b2) a hole transporting layer, such as, for example, NPD, or TCTA, (c) a light-emitting layer, comprising a fluorescent guest compound and a dibenzofuran host compound of the present invention, especially a compound A-1 to A-66, B-1 to B-18, C-1 and C-2, optionally a positive hole inhibiting layer, such as, for example, BCP, (d) an electron transporting layer, such as, for example, Alq₃, or TPBI and an inorganic compound layer, such as, for example, LiF, (e) a cathode, such as, for example, Al.

The weight ratio of compound of the formula I to the dopant in general 50:50 to 99.99:0.01, preferably 90:10 to 99.99:0.01, more preferably 95:5 to 99.9:0.1. If the guest is a phosphorescent compound, its concentration is normally 5-10%.

Accordingly, the present invention also relates to compositions comprising a compound of the present invention.

The compounds of the present invention and the above compound or compounds that can be used in a light-emitting layer may be used in any mixing ratio for forming a light-emitting layer. That is, the organic compounds of the present invention may provide a main component for forming a light-emitting layer, or they may be a doping material in another main material, depending upon a combination of the above compounds with the organic compounds of the present invention.

The hole-injecting material is selected from compounds which are capable of transporting holes, are capable of receiving holes from the anode, have an excellent effect of injecting holes to a light-emitting layer or a light-emitting material, prevent the movement of excitons generated in a light-emitting layer to an electron-injecting zone or an electron-injecting material and have the excellent capability of forming a thin film. Suitable hole-injecting materials include for example a phthalocyanine derivative, a naphthalocyanine derivative, a porphyrin derivative, oxazole, oxadiazole, triazole, imidazole, imidazolone, imidazolthione, pyrazoline, pyrazolone, tetrahydroimidazole, oxazole, oxadiazole, hydrazone, acylhydrazone, polyarylalkane, stilbene, butadiene, benzidine type triphenylamine, styrylamine type triphenylamine, diamine type triphenylamine, derivatives of these, and polymer materials such as polyvinylcarbazole, polysilane and an electroconducting polymer.

In the organic EL device of the present invention, the hole-injecting material which is more effective is an aromatic tertiary amine derivative or a phthalocyanine derivative. Although not specially limited, specific examples of the tertiary amine derivative include triphenylamine, tritolylamine, tolyldiphenylamine, N,N′-diphenyl-N,N′-(3-methylphenyl)-1,1-biphenyl-4,4′-diamine, N,N,N′,N′-tetra(4-methylphenyl)-1,1′-phenyl-4,4′-diamine, N,N,N′,N′-tetra(4-methylphenyl)-1,1′-biphenyl-4,4′-diamine, N,N′-diphenyl-N,N′-di(1-naphthyl)-1,1′-biphenyl-4,4′-diamine, N,N′-di(methylphenyl)-N,N′-di(4-n-butylphenyl)-phenanthrene-9,10-diamine, 4,4′,4″-tris(3-methylphenyl)-N-phenylamino)triphenylamine, 1,1-bis(4-di-p-tolylaminophenyl)cyclohexane, and oligomers or polymers having aromatic tertiary amine structures of these.

Although not specially limited, specific examples of the phthalocyanine (Pc) derivative include phthalocyanine derivatives or naphthalocyanine derivatives such as H₂Pc, CuPc, CoPc, NiPc, ZnPc, PdPc, FePc, MnPc, ClAlPc, ClGaPc, ClInPc, ClSnPc, Cl₂SiPc, (HO)AlPc, (HO)GaPc, VOPc, TiOPc, MoOPc, and GaPc-O—GaPc.

The hole transporting layer can reduce the driving voltage of the device and improve the confinement of the injected charge recombination within the light emitting layer, comprising the compounds of the present invention. Any conventional suitable aromatic amine hole transporting material described for the hole-injecting layer may be selected for forming this layer.

A preferred class of hole transporting materials is comprised of 4,4′-bis(9-carbazolyl)-1,1′-biphenyl compounds of the formula

wherein R⁶¹ and R⁶² is a hydrogen atom or an C₁-C₃alkyl group; R⁶³ through R⁶⁶ are substituents independently selected from the group consisting of hydrogen, a C₁-C₆alkyl group, a C₁-C₆alkoxy group, a halogen atom, a dialkylamino group, a C₆-C₃₀aryl group, and the like. Illustrative examples of 4,4′-bis(9-carbazolyl)-1,1′-biphenyl compounds include 4,4′-bis(9-carbazolyl)-1,1′-biphenyl and 4,4′-bis(3-methyl-9-carbazolyl)-1,1′-biphenyl, and the like; or 4,4′,4″-tri-(N-carbazoyl)triphenylamine (TCTA).

In addition, polymeric material can be used as a hole injection material and a hole transporting material, such as poly(N-vinylcarbazole) (PVK), polythiophenes, polypyrrole, polyaniline, and copolymers such as poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate), also called PEDOT/PSS.

The electron transporting layer is not necessarily required for the present device, but is optionally and preferably used for the primary purpose of improving the electron injection characteristics of the EL devices and the emission uniformity. Illustrative examples of electron transporting compounds, which can be utilized in this layer, include the metal chelates of 8-hydroxyquinoline as disclosed in U.S. Pat. Nos. 4,539,507, 5,151,629, and 5,150,006, the disclosures of which are totally incorporated herein by reference.

Examples of suitable electron transporting materials are metal complex compounds and nitrogen-containing five-membered ring derivatives.

Although not specially limited, specific examples of the metal complex compound include lithium 8-hydroxyquinolinate, zinc bis(8-hydroxyquinolinate), copper bis(8-hydroxyquinolinate), manganese bis(8-hydroxyquinolinate), aluminum tris(8-hydroxyquinolinate), aluminum tris(2-methyl-8-hydroxyquinolinate), gallium tris(8-hydroxyquinolinate), beryllium bis(10-hydroxybenzo[h]quinolinate), zinc bis(10-hydroxybenzo[h]quinolinate), chlorogallium bis(2-methyl-8-quinolinate), gallium bis(2-methyl-8-quinolinate)(o-cresolate), aluminum bis(2-methyl-8-quinolinate)(1-naphtholate), gallium bis(2-methyl-8-quinolinate)(2-naphtholate), gallium bis(2-methyl-8-quinolinate)phenolate, zinc bis(o-(2-benzooxazolyl)phenolate), zinc bis(o-(2-benzothiazolyl)phenolate) and zinc bis(o-(2-benzotrizolyl)phenolate). The nitrogen-containing five-membered derivative is preferably an oxazole, thiazole, thiadiazole, or triazole derivative. Although not specially limited, specific examples of the above nitrogen-containing five-membered derivative include 2,5-bis(1-phenyl)-1,3,4-oxazole, 1,4-bis(2-(4-methyl-5-phenyloxazolyl)benzene, 2,5-bis(1-phenyl)-1,3,4-thiazole, 2,5-bis(1-phenyl)-1,3,4-oxadiazole, 2-(4′-tert-butylphenyl)-5-(4″-biphenyl)1,3,4-oxadiazole, 2,5-bis(1-naphthyl)-1,3,4-oxadiazole, 1,4-bis[2-(5-phenyloxadiazolyl)]benzene, 1,4-bis[2-(5-phenyloxadiazolyl)-4-tert-butylbenzene], 2-(4′-tert-butylphenyl)-5-(4″-biphenyl)-1,3,4-thiadiazole, 2,5-bis(1-naphthyl)-1,3,4-thiadiazole, 1,4-bis[2-(5-phenylthiazolyl)]benzene, 2-(4′-tert-butylphenyl)-5-(4″-biphenyl)-1,3,4-triazole, 2,5-bis(1-naphthyl)-1,3,4-triazole and 1,4-bis[2-(5-phenyltriazolyl)]benzene. Another class of electron transport materials are oxadiazole metal chelates, such as bis[2-(2-hydroxyphenyl)-5-phenyl-1,3,4-oxadiazolato]zinc; bis[2-(2-hydroxyphenyl)-5-phenyl-1,3,4-oxadiazolato]beryllium; bis[2-(2-hydroxyphenyl)-5-(1-naphthyl)-1,3,4-oxadiazolato]zinc; bis[2-(2-hydroxyphenyl)-5-(1-naphthyl)-1,3,4-oxadiazolato]beryllium; bis[5-biphenyl-2-(2-hydroxyphenyl)-1,3,4-oxadiazolato]zinc; bis[5-biphenyl-2-(2-hydroxyphenyl)-1,3,4-oxadiazolato]beryllium; bis(2-hydroxyphenyl)-5-phenyl-1,3,4-oxadiazolato]lithium; bis[2-(2-hydroxyphenyl)-5-p-tolyl-1,3,4-oxadiazolato]zinc; b is 2-(2-hydroxyphenyl)-5-p-tolyl-1,3,4-oxadiazolato]beryllium; bis[5-(p-tert-butylphenyl)-2-(2-hydroxyphenyl)-1,3,4-oxadiazolato]zinc; bis[5-(p-tert-butylphenyl)-2-(2-hydroxyphenyl)-1,3,4-oxadiazolato]beryllium; bis[2-(2-hydroxyphenyl)-5-(3-fluorophenyl)-1,3,4-oxadiazolato]zinc; bis[2-(2-hydroxyphenyl)-5-(4-fluorophenyl)-1,3,4-oxadiazolato]zinc; bis[2-(2-hydroxyphenyl)-5-(4-fluorophenyl)-1,3,4-oxadiazolato]beryllium; bis[5-(4-chlorophenyl)-2-(2-hydroxyphenyl)-1,3,4-oxadiazolato]zinc; bis[2-(2-hydroxy phenyl)-5-(4-methoxyphenyl)-1,3,4-oxadiazolato]zinc; bis[2-(2-hydroxy-4-methylphenyl)-5-phenyl-1,3,4-oxadiazolato]zinc; bis[2-.alpha.-(2-hydroxynaphthyl)-5-phenyl-1,3,4-oxadiazolato]zinc; bis[2-(2-hydroxyphenyl)-5-p-pyridyl-1,3,4-oxadiazolato]zinc; bis[2-(2-hydroxyphenyl)-5-p-pyridyl-1,3,4-oxadiazolato]beryllium; bis[2-(2-hydroxyphenyl)-5-(2-thiophenyl)-1,3,4-oxadiazolato]zinc; bis[2-(2-hydroxyphenyl)-5-phenyl-1,3,4-thiadiazolato]zinc; bis[2-(2-hydroxyphenyl)-5-phenyl-1,3,4-thiadiazolato]beryllium; bis[2-(2-hydroxyphenyl)-5-(1-naphthyl)-1,3,4-thiadiazolato]zinc; and bis[2-(2-hydroxyphenyl)-5-(1-naphthyl)-1,3,4-thiadiazolato]beryllium, and the like.

Other suitable compounds for the electron transporting material are hetero-cyclic compounds such as benzimidazole derivatives, benzoxazole derivatives, oxadiazole derivatives, thiadiazole derivative, triazole derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, quinoline derivatives, benzoquinoline derivatives, oligo-pyridine derivatives, e.g. bipyridine derivatives and terpyridine derivatives, naphthylidine derivatives, indole derivatives and naphthalimide derivatives; silole derivatives; and phosphineoxide derivatives.

The property of charge injection can be improved by adding an electron-accepting compound to the hole injection layer and/or the hole transporting layer and electron-donating material to the electron transporting layer.

It is possible to add reducing dopant to the electron transporting layer to improve the EL device property. The reducing dopant is a material that can reduce the electron transporting material. Examples of the reducing dopant are alkaline metals, e.g. Na, K, Rb and Cs, and alkaline earth metals, e.g. Ca, Sr, and Ba.

The organic EL device of the present invention may comprise an inorganic compound layer between at least one of the electrodes and the above organic thin layer. Examples of the inorganic compound used for the inorganic compound layer include various types of oxides, nitrides and oxide nitrides such as alkali metal oxides, alkaline earth metal oxides, rare earth oxides, alkali metal halides, alkaline earth metal halides, rare earth halides, SiO_(x), AlO_(x), SiN_(x), SiON, AlON, GeO_(x), LiO_(x), LiON, TiO_(x), TiON, TaO_(x), TaON, TaN_(x) and C. In particular, as the component contacting the anode, SiO_(x), AlO_(x), SiN_(x), SiON, AlON, GeO_(x) and C are preferred since a suitable interface layer of injection is formed. As the component contacting the cathode LiF, MgF₂, CaF₂ and NaF are preferred.

In the organic EL device of the present invention, the light-emitting layer may contain, in addition to the light-emitting organic material of the present invention, at least one of other light-emitting material, other dopant, other hole-injecting material and other electron-injecting material. For improving the organic EL device of the present invention in the stability against temperature, humidity and ambient atmosphere, a protective layer may be formed on the surface of the device, or the device as a whole may be sealed with a silicone oil, or the like.

The electrically conductive material used for the anode of the organic EL device is suitably selected from those materials having a work function of greater than 4 eV. The electrically conductive material includes carbon, aluminum, vanadium, iron, cobalt, nickel, tungsten, silver, gold, platinum, palladium, alloys of these, metal oxides such as tin oxide and indium oxide used for ITO substrates or NESA substrates, and organic electroconducting polymers, such as polythiophene and polypyrrole.

The electrically conductive material used for the cathode is suitably selected from those having a work function of smaller than 4 eV. The electrically conductive material includes magnesium, calcium, tin, lead, titanium, yttrium, lithium, ruthenium, manganese, aluminum and alloys of these, while the electrically conductive material shall not be limited to these. Examples of the alloys include magnesium/silver, magnesium/indium and lithium/aluminum, while the alloys shall not be limited to these. Each of the anode and the cathode may have a layer structure formed of two layers or more as required.

For the effective light emission of the organic EL device, at least one of the electrodes is desirably sufficiently transparent in the light emission wavelength region of the device. Further, the substrate is desirably transparent as well. The transparent electrode is produced from the above electrically conductive material by a deposition method or a sputtering method such that a predetermined light transmittance is secured. The electrode on the light emission surface side has for instance a light transmittance of at least 10%. The substrate is not specially limited so long as it has adequate mechanical and thermal strength and has transparency. For example, it is selected from glass substrates and substrates of transparent resins such as a polyethylene substrate, a polyethylene terephthalate substrate, a polyether sulfone substrate and a polypropylene substrate.

In the organic EL device of the present invention, each layer can be formed by any one of dry film forming methods such as a vacuum deposition method, a sputtering method, a plasma method and an ion plating method and wet film forming methods such as a spin coating method, a dipping method and a flow coating method. The thickness of each layer is not specially limited, while each layer is required to have a proper thickness. When the layer thickness is too large, inefficiently, a high voltage is required to achieve predetermined emission of light. When the layer thickness is too small, the layer is liable to have a pinhole, etc., so that sufficient light emission brightness is hard to obtain when an electric field is applied. The thickness of each layer is for example in the range of from about 5 nm to about 10 μm, for instance about 10 nm to about 0.2 μm.

In the wet film forming method, a material for forming an intended layer is dissolved or dispersed in a proper solvent, such as toluene, ethanol, chloroform, tetrahydrofuran and dioxane, and a thin film is formed from the solution or dispersion. The solvent shall not be limited to the above solvents. For improving the film formability and preventing the occurrence of pinholes in any layer, the above solution or dispersion for forming the layer may contain a proper resin and a proper additive. The resin that can be used includes insulating resins such as polystyrene, polycarbonate, polyarylate, polyester, polyamide, polyurethane, polysulfone, polymethyl methacrylate, polymethyl acrylate and cellulose, copolymers of these, photoconductive resins such as poly-N-vinylcarbozole and polysilane, and electroconducting polymers such as polythiophene and polypyrrole. The above additive includes an antioxidant, an ultraviolet absorbent and a plasticizer.

When the light-emitting organic material of the present invention is used in a light-emitting layer of an organic EL device, an organic EL device can be improved in organic EL device characteristics such as light emission efficiency and maximum light emission brightness. Further, the organic EL device of the present invention is remarkably stable against heat and electric current and gives a usable light emission brightness at a low actuation voltage. The problematic deterioration of conventional devices can be remarkably decreased.

The organic EL device of the present invention has significant industrial values since it can be adapted for a flat panel display of an on-wall television set, a flat light-emitting device, a light source for a copying machine or a printer, a light source for a liquid crystal display or counter, a display signboard, lighting application and a signal light.

The material of the present invention can be used in the fields of an organic EL device, an electrophotographic photoreceptor, a photoelectric converter, a solar cell, and an image sensor.

Various features and aspects of the present invention are illustrated further in the examples that follow. While these examples are presented to show one skilled in the art how to operate within the scope of this invention, they are not to serve as a limitation on the scope of the invention where such scope is only defined in the claims. Unless otherwise indicated in the following examples and elsewhere in the specification and claims, all parts and percentages are by weight.

EXAMPLES Example 1 Synthesis of 2,8-Bis-((E)-styryl)-dibenzofuran

1a) 2,8-Dibromodibenzofuran

Bromine (92.6 g, 0.58 mol) in acetic acid (54 g) is added at 75° C. to a solution of dibenzofuran (23.2 g, 0.14 mol) in acetic acid (232 g). The mixture is then stirred at 75° C. for 3 hours. The reaction mixture is cooled to room temperature and poured into H₂O. The orange solid is washed with Na₂S₂O₃ aq. and H₂O. The crude product is then purified by recrystallization from n-hexane, wherein the pure product is obtained as a white solid (38% yield; mp.: 226° C.).

¹H-NMR (CDCl₃, ppm): 7.65 (d, 2H), 7.59 (dd, 2H), 8.03 (d, 2H).

1b) 2,8-Bis-((E)-styryl)-dibenzofuran

Tetrethylamine hydroxide (13.6 g, 18.4 mmol), tetrakis(triphenylphosphine)palladium(0) (142 mg) and trans-2-phenylvinylboronic acid (2.3 g, 15.3 mmol) are added to a solution of the product from example 1a) (2.00 g, 6.14 mmol) in N,N′-Dimethylacetamide (DMA) (30 ml). The mixture is then stirred at 110° C. for 24 hours. The reaction mixture is cooled to room temperature and poured into H₂O. A gray crude product is obtained after filtration and washing with n-hexane. The crude product is purified by silicagel column chromatography with CH₂Cl₂, which result in a white solid (71% yield, mp.: 226° C.).

¹H-NMR (CDCl₃, ppm): 7.26-7.30 (m, 6H), 7.39 (t, 4H), 7.54-7.58 (m, 6H), 7.65 (dd, 2H), 8.12 (d, 2H)

Example 2 Synthesis of 1,5-dibenzofuranyl-3,7-di-tert-butylnaphthalene

2a) 1,5-dibromo-3,7-di-tert-butylnaphthalene

Fe (212 mg) and bromine (18.3 g, 0.11 mol) in carbontetrachloride (75 ml) are added at 0° C. to a solution of 2,6-di-tert-butylnaphthalene (25 g, 0.1 mol) in carbontetrachloride (300 ml). The mixture is then stirred at 0° C. for 3.5 hours. The reaction mixture is poured into H₂O and then the organic layer is washed with Na₂S₂O₃ aq. and H₂O. The organic layer is dried over MgSO₄ and concentrated by evaporation. The crude product is then purified by silicagel column chromatography with n-hexane, which result in a white solid (31% yield; mp.: 226° C.).

¹H-NMR (CDCl₃, ppm): 1.41 (s, 18H), 7.88 (d, 2H), 8.11 (d, 2H).

2b) 1,5-Dibenzofuranyl-3,7-di-tert-butylnaphthalene

Tetrethylaminehydroxide (3.5 g, 14.2 mmol), tetrakis(triphenylphosphine)palladium(0) (100 mg) and 4-denzofuranboronic acid (3 g, 14.0 mmol) are added to a solution of the product from example 2a) (1.88 g, 4.72 mmol) in DMA (30 ml). The mixture is stirred at 110° C. for 1 hour, then cooled to room temperature, whereby a yellow solid product is obtained which is isolated by filtration and washed with H₂O. The yellow solid is then dissolved in CH₂Cl₂ and dried over MgSO₄. Concentration by evaporation and silicagel column chromatography with ethylacetate/hexane=1/30 as eluent afforded a pure yellow solid product (65% yield; mp.: 226° C.).

¹H-NMR (CDCl₃, ppm): 1.98 (s, 18H), 7.38-7.58 (m, 8H), 7.67 (d, 2H), 7.77 (d, 2H), 7.82 (d, 2H), 8.08 (dd, 2H), 8.11 (dd, 2H).

The compounds shown below (examples 3-10) are prepared in analogues manner using the appropriate educts.

Example Structure Mp. [° C.] 3

247 4

290 5

255 6

7

230 8

9

10 

Example 11 Synthesis of 2-Phenanthren-9-yl-8-pyren-1-yl-dibenzofuran

11a) 2-Bromodibenzofuran

Bromine (23.8 g, 0.156 mol) in acetic acid (5 g) is added at 50° C. to a solution of dibenzofuran (25 g, 0.149 mol) in acetic acid (230 g). The mixture is then stirred at 50° C. for 4 hours. The reaction mixture is cooled to room temperature and poured into H₂O. The orange solid is washed with Na₂S₂O₃ aq. and H₂O. The crude product is then purified by recrystallization from toluene/CH₂Cl₂, wherein the pure product is obtained as a white solid (13% yield).

¹H-NMR (CDCl₃, ppm): 7.59-7.73 (m, 5H), 7.90 (d, 1H), 8.70 (d, 1H)

11b) 2-Bromo-8-iododibenzofuran

2-Bromodibenzofuran (2.5 g, 10.1 mmol), orthoperiodic acid (0.49 g, 2.15 mmol), iodine (1.02 g, 4.02 mmol), sulfuric acid, H₂O (2 ml) and acetic acid (10 ml) are put into a reaction vessel and the mixture is stirred at 70° C. for 3 hours. After cooling to room temperature the reaction mixture is poured into water and filtered. The white solid is washed by methanol and the desired product is obtained (1.92 g, 51%).

¹H-NMR (CDCl₃, ppm): 7.34 (d, 1H), 7.44 (d, 1H), 7.57 (dd, 1H), 7.75 (dd, 1H), 8.01 (d, 1H), 8.22 (d, 1H)

11c) 2-Bromo-8-pyren-1-yl-dibenzofuran

20% aq. solution of tetraethylammoninm hydroxide (5.33 g, 7.24 mmol), tetrakis-(triphenylphosphine)palladium(0) (200 mg) and 1-(4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl) pyrene (1.74 g, 5.3 mmol) are added to a solution of the product of example 11b) (1.81 g, 4.83 mmol) in N,N′-dimethylacetamide (DMA) (70 ml). The mixture is then stirred at 120° C. for 3 hours. The reaction mixture is cooled down to room temperature and poured into H₂O. A gray crude product is obtained after filtration and washing with n-hexane. The crude product is purified by silicagel column chromatography with hexane/CH₂Cl₂—, which result in a white solid (71% yield).

¹H-NMR (CDCl₃, ppm): 7.53 (d, 1H), 7.61 (dd, 1H), 7.75 (d, 2H), 8.01-8.28 (m, 12H)

11d) 2-Phenanthren-9-yl-8-pyren-1-yl-dibenzofuran (A-17) is prepared in analogy to example 2b) using the compound obtained in step 11c) and 9-(4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl) phenanthrene.

¹H-NMR (CDCl₃, ppm): 7.53-7.57 (m, 1H), 7.60-7.70 (m, 4H), 7.74-7.83 (m, 4H), 7.90-8.00 (m, 2H), 8.01-8.09 (m, 3H), 8.15 (d, 2H), 8.15-8.26 (m, 6H), 8.74 (d, 1H), 8.80 (d, 1H)

The compounds of examples 12 and 13, which are shown below, are prepared in analogues manner to example 11 using the appropriate educts.

Example 12 Diphenyl-[4-(8-pyren-1-yl-di benzofuran-2-yl)-phenyl]-amine

¹H-NMR (CDCl₃, ppm): 7.00-7.06 (m, 2H), 7.12-7.18 (m, 6H), 7.24-7.28 (m, 3H), 7.54-7.58 (d, 2H), 7.64-7.78 (m, 4H), 8.01-8.28 (m, 12H)

Example 13 2-Naphthalen-2-yl-8-pyren-1-yl-dibenzofuran

¹H-NMR (CDCl₃, ppm): 7.46-7.53 (m, 2H), 7.73-7.96 (m, 8H), 8.01-8.15 (m, 6H), 8.17-8.29 (m, 5H), 8.32 (d, 1H)

Example 14 9,10-Bis-di benzofuran-4-yl-2,6-di-tert-butyl-anthracen

Compound B-14 is prepared in analogues manner to example 2 using the appropriate educts.

¹H-NMR (CDCl₃, ppm): 1.15 (s, 18H), 7.35-7.43 (m, 8H), 7.58-7.67 (m, 8H), 8.08-8.12 (m, 2H), 8.18 (dd, 2H)

Example 15 Synthesis of 4-(2,6-Di-tert-butyl-10-naphthalen-2-yl-anthracen-9-yl)-dibenzofuran

15a) 9-Bromo-2,6-di-tert-butyl-anthracene

Bromine (3.02 g, 18.9 mmol) is added at 0° C. to a solution of 2,6-di-tert-butylanthracene (5.0 g, 17.2 mol) in carbontetrachloride (200 ml). The mixture is then stirred at 0° C. for 15 hours. After allowing to heat up to room temperature, half the amount of solvent is evaporated and the resulting mixture is poured into methanol. The precipitate is collected by filtration, recrystallized from n-hexane/methanol and the desired product is obtained as a white solid (1.13 g).

¹H-NMR (CDCl₃, ppm): 1.47 (s, 9H), 1.48 (s, 9H), 7.58 (dd, 1H), 7.67 (dd, 1H), 7.85 (d, 1H), 7.91 (d, 1H), 8.33 (s, 1H), 8.38 (d, 1H), 8.43 (d, 1H)

15b) 9-Bromo-2,6-di-tert-butyl-10-iodo-anthracene

Iodination is done in the same manner as described in example 11b) using the compound obtained in example 15a) as starting material.

¹H-NMR (CDCl₃, ppm): 1.48 (2s, 18H), 7.65-7.72 (m, 2H), 8.42-8.52 (m, 4H)

15c) 4-(10-Bromo-2,6-di-tert-butyl-anthracen-9-yl)-dibenzofuran

The compound shown above is prepared in the same manner as described in example 11c) using the compound obtained in example 15b) and 1-dibenzofuranylboronic acid as starting materials.

¹H-NMR (CDCl₃, ppm): 1.18 (s, 9H), 1.46 (s, 9H), 7.29-7.33 (m, 1H), 7.35-7.42 (m, 3H), 7.48-7.59 (m, 4H), 7.68 (dd, 1H), 8.07 (m, 1H), 8.15 (dd, 1H), 8.53 (d, 1H), 8.58 (d, 1H)

15d) 4-(2,6-Di-tert-butyl-10-naphthalen-2-yl-anthracen-9-yl)-dibenzofuran (A-35) is prepared in the same manner as described in example 2b) using the compound obtained in step 15c) and 2-(4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl) naphthalene as starting materials.

¹H-NMR (CDCl₃, ppm): 1.16 (s, 9H), 1.21 (s, 9H), 7.35-7.42 (m, 5H), 7.55-7.73 (m, 9H), 7.92-7.97 (m, 1H), 8.01-8.11 (m, 4H), 8.16-8.19 (m, 1H)

Example 16 4-(2,6-Di-tert-butyl-10-pyren-1-yl-anthracen-9-yl)-dibenzofuran

Example 15 is repeated except using 1-(4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl) pyrene in the last step.

¹H-NMR (CDCl₃, ppm): 1.05 (s, 9H), 1.14 (s, 9H), 7.24-8.44 (m, 22H)

Example 17 2,6-Di-pyren-1-yl-dibenzofuran

17a) 6-Bromo-2-iodo-dibenzofuran

6-Bromo-2-iodo-dibenzofuran is prepared in the same manner as described in example 11b), except using 4-bromodibenzofurane as a starting material.

¹H-NMR (CDCl₃, ppm): 7.22-7.27 (t, 1H), 7.42-7.45 (d, 1H), 7.62-7.66 (dd, 1H), 7.75-7.79 (dd, 1H), 7.82-7.85 (dd, 1H), 8.26 (d, 1H)

17b) 6-Bromo-2-pyren-1-yl-dibenzofuran

6-Bromo-2-pyren-1-yl-dibenzofuran is prepared in the same manner as described in example 11c), except using 6-Bromo-2-iodo-dibenzofuran as a starting material.

¹H-NMR (CDCl₃, ppm): 7.24-7.28 (t, 1H), 7.65-7.68 (dd, 1H), 7.74-7.77 (dd, 1H), 7.82-7.85 (d, 1H), 7.91-7.94 (dd, 1H), 8.01-8.06 (m, 3H), 8.12-8.27 (m, 7H)

17c) 2,6-Di-pyren-1-yl-dibenzofuran (A-58)

A-58 is prepared in analogy to A-17 using the appropriate educts.

¹H-NMR (CDCl₃, ppm): 7.58-7.62 (m, 2H), 7.67-7.74 (m, 2H), 8.02-8.10 (m, 6H), 8.13-8.30 (m, 13H), 8.35-8.38 (d, 1H)

Example 18 6-Phenanthren-9-yl-2-pyren-1-yl-dibenzofuran

A-59 is prepared in analogy to A-58 using the appropriate educts.

¹H-NMR (CDCl₃, ppm): 7.52-7.61 (m, 3H), 7.63-7.80 (m, 6H), 7.95-8.28 (m, 13H), 8.80-8.83 (d, 1H), 8.84-8.88 (d, 1H)

Example 19

A-60 is prepared in analogy to A-17 using the appropriate educts.

¹H-NMR (CDCl₃, ppm): 6.64-6.89 (m, 5H), 7.04-7.46 (m, 11H), 8.0-8.26 (m, 14H)

Example 20

A-61 is prepared in analogy to A-58 using the appropriate educts.

¹H-NMR (CDCl₃, ppm): 6.62-6.86 (m, 5H), 7.02-7.14 (m, 5H), 7.30-7.40 (m, 5H), 7.58 (s, 1H), 7.66-8.26 (m, 14H)

Application Examples Application Example 1

Compounds A-1, B-1, C-1, C-2, A-9, A-10 and A-7, respectively are deposited under vacuum on a glass plate in a thickness of 60 nm. Fluorescence spectra of the deposited films are measured by fluorescence spectrophotometer (F-4500, HITACHI). The emission λ_(max) is shown below.

Compound Emission λ_(max) [nm] A-1 421 B-1 383 C-1 420 C-2 387 A-9 364 A-10 474 A-7 454

Application Example 2

The following device structure is prepared: ITO/CuPC/TCTA/Compound B-1/TPBI/LiF/Al where ITO is indium tin oxide, CuPC is copper phthalocyanine, TCTA is 4,4′,4″-tri-(N-carbazoyl)triphenylamine and TPBI is 1,3,5-tris-(N-phenyl-benzimidazol-2-yl)benzene. Using this device structure, a brightness of 50 cd/m² is observed at 100 mA/cm².

Application Example 3

The following device structure is prepared: ITO/CuPC/TCTA/Compound B-1+Compound G-1 (1.1% by weight)/TP131/LiF/Al. Using this device structure, a brightness of 500 cd/m² is observed at 100 mA/cm².

Application Example 4

The following device structure is prepared: ITO/CuPC/TCTA/Compound C-2/TPBI/LiF/Al. Using this device structure, a brightness of 120 cd/m² is observed at 100 mA/cm².

Application Example 5

The following device structure is prepared: ITO/CuPC/TCTA/Compound C-2+Compound G-1 (1.9% by weight)/TP131/LiF/Al. Using this device structure, a brightness of 70 cd/m² is observed at 100 mA/cm².

Application Example 6

The following device structure is prepared: ITO/CuPC/NPD/Compound B-1/TPBI/LiF/Al where NPD is N,N′-Di(naphthalene-1-yl)-N,N′-diphenyl-benzidine. Using this device structure, a brightness of 370 cd/m² is observed at 100 mA/cm2.

Application Example 7

The following device structure is prepared: ITO/CuPC/NPD/Compound B-1+TBPe (1.4%)/TPBI/LiF/Al where TPBe is 2,5,8,11-tetra-t-butylperylene. Using this device structure, a brightness of 680 cd/m² is observed at 88 mA/cm².

Application Example 8

The following device structure is prepared: ITO/CuPC/NPD/Compound A-10/TPBI/LiF/Al. Using this device structure, a brightness of 3,800 cd/m² is observed at 111 mA/cm2.

Application Example 9

The following device structure is prepared: ITO/CuPC/NPD/Compound A-10+TBPe (1.5%)/TPBI/LiF/Al. Using this device structure, a brightness of 2,030 cd/m² is observed at 90 mA/cm².

Application Examples 10 to 21

The following device structure is prepared: ITO/CuPC/NPD/Emitting layer (dibenzofuran of the present invention as a host+TBPe as a guest)/TPBI/LiF/Al. Using this device structure, bright blue EL emission is observed. The EL properties of the devices are summarized in Table 1.

TABLE 1 EL properties obtained in application exampleS 10 TO 21 Guest (TBPe) Appli- Concen- Current Emission cation tration Brightness Efficiency Voltage peak Example Host (%) (cd/m²) (cd/A) (V) (nm) 10 C-2 2.4 158 2.5 10 467, 493 11 C-1 1.7 99 1.1 7 462, 489 12 A-17 — 133 3.3 7.4 465 13 A-17 1.6 79 4.0 7.2 467, 492 14 B-14 — 86 2.2 7.6 459 15 B-14 1.8 97 4.9 7.1 462, 490 16 A-57 — 108 2.7 8.3 460 17 A-57 1.6 95 2.4 8.1 464, 489 18 A-43 — 120 3.0 5.1 461 19 A-43 1.5 96 4.8 4.7 465, 491 20 A-50 — 139 3.5 6.8 466 21 A-50 1.5 88 4.4 6.4 467, 492 22 A-35 — 86 4.3 7.6 467 23 A-35 1.3 98 4.9 7.4 461, 488 24 A-58 — 104 5.2 6.4 465 25 A-58 2.1 89 4.4 6.7 467, 490

Application Example 26

The following device structure is prepared: ITO/CuPC/NPD/Emitting layer (dibenzofuran of the present invention as a host+dibenzofuran of the present invention as a guest)/TPBI/LiF/Al. Using this device structure, bright blue EL emission is observed. The EL properties of the device is summarized in Table 2.

TABLE 2 EL properties obtained in application example 26 Current Emission Application Brightness Efficiency Voltage Peak Example Host Guest (cd/m²) (cd/A) (V) (nm) 26 A-17 B-14 83 2.1 7.5 462 (5.1%) 

The invention claimed is:
 1. An electroluminescent device, comprising in the light emitting layer a compound of the formula

and a phosphorescent metal complex of Ir, Pt, Eu, Ru, Rh, Pd, Ag, Re, Os and Au as dopant, wherein R⁸¹ and R⁸⁸ are independently of each other H, —OR²⁰¹, —SR²⁰² and/or —NR²⁰³R²⁰⁴, C₁-C₂₄alkyl; C₁-C₂₄alkyl, which is substituted by E and/or interrupted by D; C₂-C₁₈alkenyl, C₂-C₁₈alkenyl, which is substituted by E, C₃-C₈cycloalkyl, C₃-C₈cycloalkyl, which is substituted by G, aryl, aryl, which is substituted by G, heteroaryl, or heteroaryl, which is substituted by G, silyl,

SiR⁶²R⁶³R⁶⁴, —CN, cyclic ether, —B(OR⁶⁵)₂ and/or halogen, wherein R²⁰¹ is hydrogen, C₁-C₂₄alkyl, C₁-C₂₄alkyl, which is substituted by E and/or interrupted by D; C₂-C₁₂alkenyl, C₃-C₆alkenoyl, C₃-C₈cycloalkyl, or benzoyl, each of which may optionally be substituted by one or more groups C₁-C₆alkyl, halogen, —OH and/or C₁-C₄alkoxy; phenyl, naphthyl, phenanthryl, anthranyl, or pyrenyl, each of which may optionally be substituted by halogen, —OH, C₁-C₁₂alkyl, C₁-C₁₂alkoxy, phenoxy, C₁-C₁₂alkylsulfanyl, phenylsulfanyl, —N(C₁-C₁₂alkyl)₂ and/or diphenylamino; R²⁰² is C₁-C₂₄alkyl, C₁-C₂₄alkyl, which is substituted by E and/or interrupted by D; C₂-C₁₂alkenyl, C₁-C₈alkanoyl, C₂-C₁₂alkenyl, C₃-C₆alkenoyl; C₃-C₈cycloalkyl, or benzoyl, each of which may optionally be substituted by one or more groups C₁-C₆alkyl, halogen, —OH, C₁-C₄alkoxy or C₁-C₄alkylsulfanyl; phenyl, naphthyl, phenanthryl, anthranyl, or pyrenyl, each of which may optionally be substituted by halogen, C₁-C₁₂alkyl, C₁-C₁₂alkoxy, phenyl-C₁-C₃alkyloxy, phenoxy, C₁-C₁₂alkylsulfanyl, phenylsulfanyl, —N(C₁-C₁₂alkyl)₂, diphenylamino, —(CO)O(C₁-C₈alkyl), —(CO)—C₁-C₈alkyl, or (CO)N(C₁-C₈alkyl)₂; R²⁰³ and R²⁰⁴ are independently of each other hydrogen, C₁-C₂₄alkyl, C₁-C₂₄alkyl, which is substituted by E and/or interrupted by D; C₂-C₂alkenyl, C₃-C₈cycloalkyl, or benzoyl, each of which may optionally be substituted by one or more groups C₁-C₆alkyl, halogen, —OH, or C₁-C₄alkoxy; phenyl-C₁-C₃alkyl, C₁-C₈alkanoyl, C₃-C₁₂alkenoyl; phenyl naphthyl, phenanthryl, anthranyl, or pyrenyl, each of which is optionally substituted by C₁-C₁₂alkyl, benzoyl or C₁-C₁₂alkoxy; or R²⁰³ and R²⁰⁴ together are C₂-C₈alkylene, or branched C₂-C₈alkylene optionally interrupted by —O—, —S—, or —NR²⁰⁵— and/or optionally substituted by hydroxyl, C₁-C₄alkoxy, C₂-C₄alkanoyloxy, or benzoyloxy, wherein the ring formed by R²⁰³ and R²⁰⁴ can optionally be condensed one or two times by phenyl which can be substituted one to three times with C₁-C₈-alkyl, C₁-C₈-alkoxy, halogen, or cyano; R²⁰⁵ is hydrogen, C₁-C₂₄alkyl, C₁-C₂₄alkyl, which is substituted by E and/or interrupted by D; C₂-C₅alkenyl, C₃-C₈cycloalkyl, phenyl-C₁-C₃alkyl, C₁-C₈alkanoyl, C₃-C₁₂alkenoyl; benzoyl; phenyl, naphthyl, phenanthryl, anthranyl, or pyrenyl, each of which is optionally substituted by C₁-C₁₂alkyl, benzoyl, or C₁-C₁₂alkoxy; D is —CO—, —COO—, —OCOO—, —S—, —SO—, —SO₂—, —O—, —NR⁵—, —SiR⁶¹R⁶²—, —POR⁵—, —CR⁶³═CR⁶⁴—, or —C≡—; E is halogen, C₆-C₁₄aryl, which may be substituted by —OR⁵, —SR⁵, —NR⁵R⁶,

SiR^(62′)R^(63′)R^(64′), wherein R^(62′), R^(63′) and R^(64′) are independently of each other a C₁-C₈alkyl group, a C₆-C₂₄aryl group or a C₇-C₁₂aralkyl group, —CN, cyclic ether and/or —B(OR⁶⁵)₂, wherein R⁶⁵ is hydrogen, C₁-C₂₄alkyl, C₃-C₈cycloalkyl, C₇-C₂₄aralkyl, C₂-C₁₈alkenyl, C₂-C₂₄alkynyl, hydroxy, mercapto, C₁-C₂₄alkoxy, C₁-C₂₄alkylthio, C₆-C₃₀aryl, C₂-C₃₀heteroaryl, halogen, haloalkane, silyl, siloxanyl, and an alicyclic ring formed with adjacent substituents R⁶⁵; —OR⁵, —SR⁵, —NR⁵R⁶, —COR⁸, —COOR⁷, —CONR⁵R⁶, —CN, halogen, silyl, C₁-C₁₈alkyl, or heteroaryl, G is E, or C₁-C₁₈alkyl, wherein R⁵ and R⁶ are independently of each other H, C₆-C₁₈aryl; C₆-C₁₈aryl which is substituted by C₁-C₁₈alkyl, C₁-C₁₈alkoxy, or silyl; C₁-C₁₈alkyl or C₁-C₁₈alkyl which is interrupted by —O—; or R⁵ and R⁶ together form a five or six membered ring, R⁷ is H, C₆-C₁₈aryl, C₇-C₁₂alkylaryl, which are optionally substituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl; or C₁-C₁₈alkyl which is interrupted by —O—; R⁸ is C₆-C₁₈aryl; C₆-C₁₈aryl which is substituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl, C₇-C₁₂alkylaryl, or C₁-C₁₈alkyl which is interrupted by —O—; R⁶¹ and R⁶² are independently of each other C₆-C₁₈aryl; C₆₋₁₈aryl which is substituted by C₁-C₁₈alkyl, C₁-C₁₈alkoxy; or C₁-C₁₈alkyl which is interrupted by —O—, R⁶³ and R⁶⁴ are independently of each other H, C₆-C₁₈aryl; C₆₋₁₈aryl which is substituted by C₁-C₁₈alkyl, C₁-C₁₈alkoxy; or C₁-C₁₈alkyl which is interrupted by —O—, wherein R⁸², R⁸³, R⁸⁶ and R⁸⁷ are independently of each other a group of the formula —(W¹)_(a)—(W²)_(b)—W³, a and b are 0, or 1, W¹ and W² are independently of each other a group of formula

and R¹¹, R^(11′), R¹², R^(12′), R¹³, R^(13′), R¹⁵, R^(15′), R¹⁶, R^(16′), R¹⁷ and R^(17′) are independently of each other H, E, tri(C₁-C₈alkyl)silyl, C₆-C₁₈aryl; C₆-C₁₈aryl which is substituted by G; C₁-C₁₈alkyl; C₁-C₁₈alkyl which is substituted by E and/or interrupted by D; C₁-C₁₈alkoxy; or C₁-C₁₈alkoxy which is substituted by E and/or interrupted by D; C₇-C₁₈aralkyl; or C₇-C₁₈aralkyl which is substituted by G; R¹⁸ and R¹⁹ are independently of each other C₁-C₁₈alkyl; C₁-C₁₈alkoxy, C₆-C₁₈aryl; C₇-C₁₈aralkyl; or R¹⁸ and R¹⁹ together form a ring, which can optionally be substituted by C₁-C₈alkyl, W³ is a group of formula —NR⁷⁰R⁷¹, wherein R⁷⁰ and R⁷¹ are independently of each other a group of formula

wherein R⁷², R⁷³ and R⁷⁴ are independently of each other hydrogen, C₁-C₈alkyl, a hydroxyl group, a mercapto group, C₁-C₈alkoxy, C₁-C₈alkylthio, halogen, halo-C₁-C₈alkyl, a cyano group, an aldehyde group, a ketone group, a carboxyl group, an ester group, a carbamoyl group, an amino group, a nitro group, a silyl group or a siloxanyl group, or R⁷⁰ and R⁷¹ together with the nitrogen atom to which they are bonded form a five or six membered heterocyclic ring, which can be condensed by one or two optionally substituted phenyl groups; with the proviso that b is 1, if R⁷⁰ and R⁷¹ are independently of each other a group of formula


2. The electroluminescent device according to claim 1, wherein the light emitting layer comprises a compound of formula

wherein R⁸¹, R⁸³, R⁸⁶ and R⁸⁸ are as defined in claim
 1. 3. The electroluminescent device according to claim 1, wherein the light emitting layer comprises a compound of formula

wherein R⁸¹ and R⁸³ are independently of each other H, or NR²⁰³R²⁰⁴, R²⁰³ and R²⁰⁴ together form a five membered ring, wherein the ring formed by R²⁰³ and R²⁰⁴ can optionally be condensed one or two times by phenyl; R⁸⁶ and R⁸⁸ are independently of each other a group of the formula —(W¹)_(a)—(W²)_(b)—W³, a and b are 0, or 1, W¹ and W² are independently of each other a group of formula

R¹¹, R^(11′), R¹² and R^(12′) R are H; and W³ is a group of formula —NR⁷⁰R⁷¹, wherein R⁷⁰ and R⁷¹ together with the nitrogen atom to which they are bonded form a five or six membered heterocyclic ring, which can be condensed by one or two optionally substituted phenyl groups.
 4. The electroluminescent device according to claim 1, wherein the compound of formula (Ia) is a compound of formula


5. A method of forming a light emitting layer of an electroluminescent device by incorporating the compounds of formula (Ia), (Ib), or (Ic) according to claim 1 with phosphorescent metal complexes of Ir, Pt, Eu, Ru, Rh, Pd, Ag, Re, Os and Au as a dopant therein. 